Unified orifice filter/muffler expansion controller

ABSTRACT

A refrigerant expansion means for an automobile air conditioning system of the type employing a small diameter tube to pass refrigerant from the condenser to the evaporator. An unpleasant and sometimes alarming hissing noise which is characteristically emitted by this type of expansion means when the compressor is de-activated is muffled by a cup-shaped member around the outlet of the tube. This member may be of porous sintered metal material which readily passes refrigerant therethrough but blocks much of the noise emitted at the tube&#39;&#39;s outlet and prevents it from passing to the occupant of the automobile.

United States Patent 1191 Scherer et a].

[ June H, 1974 UNIFIED 011111611 FILTER/MUFFLER EXPANSION CONTROLLER Inventors: Carl A. Scherer, Clarence Center;

Hugh J. Muirhead, Ransomville, both of NY.

General Motors Corporation, Detroit, Mich.

Filed: Oct. 30, 1972 Appl. No.: 302,108

Assignee:

Int. Cl. F25d 19/00 Field of Search 62/296, 51 1 References Cited UNITED STATES PATENTS l l/ l95l 2,576,6l0 Kunzog 62/5ll us. c1. 62/296, 62/511 Primary Examiner- Meyer Perlin Attorney, Agent, or Firm-K. H. MacLean, Jr.

[57] ABSTRACT A refrigerant expansion means for an automobile air conditioning system of the type employing a small diameter tube to pass refrigerant from the condenser to the evaporator. An unpleasant and sometimes alarm- I ing hissing noise which is characteristically emitted by this type of expansion means when the compressor is de-activated is muffled by a cup-shaped member around the outlet of the tube. This member may be of porous sintered metal material which readily passes refrigerant therethrough but blocks much of the noise emitted at the tubes outlet and prevents it from passing to the occupant of the automobile.

3 Claims, 4 Drawing Figures 3/1952 Shawhan 62/51] 7 PATENTEDJun 11 1914 w /0 6!" v82 W UNIFIED ORIFICE FILTER/MUFFLER EXPANSION CONTROLLER This invention relates to automobile air conditioning systems and particularly to capillary tube type refrigerant expansion devices.

Air conditioning systems have previously used capillary tube type expansion devices for reducing pressure of refrigerant prior to passage into the evaporator for vaporization. Capillary tube expansion means have usually included relatively long, small diameter tubes but also include short, small diameter tubes both of which reduce refrigerant pressure by the well-known throttling process A disadvantage with prior capillary tube type expanders has been the unpleasant and often alarming hissing noise which is emitted as the refrigerant compressor is de-activated. This noise is caused by the passage of gaseous refrigerant which is produced in the condenser immediately after the compressor is shut down through the orifice tube. The gaseous refrigerant passes through the tube at a higher velocity than the passage of liquid refrigerant through the orifice tube when the compressor is operating. The hissing noise is unpleasant and often alarming to a nontechnically acquainted operator of an automobile. Thus, even though the hissing noise is harmless, it is desirable to eliminate the noise.

Another problem with capillary tube type expanders is their susceptibility to clogging by any foreign material carried by refrigerant in the system. Although a great amount of care is usually employed to keep the system as clean as possible during assembly and charging with refrigerant, there is a good probability that some foreign particles will still be present in the system. When a foreign particle does lodge itself firmly within the small diameter capillary or orifice tube, the cooling capacity of the air conditioning system may be greatly diminished.

More particularly, the subject expansion device includes a housing with a member therein supporting a relatively short length, small diameter tube for passing refrigerant and thus reducing its pressure. The supporting member also retains a cup-shaped strainer around the inlet end of the orifice tube and a similar cupshaped muffler around the outlet end of the orifice tube. The strainer and muffler members may be of a sintered metal such as brass or bronze which will quite readily pass fluid but will also entrap small particles and muffle noise. Although the muffler around the outlet of the orifice tube is primarily utilized to reduce the sibilant or hissing sound of gas flow through the orifice tube, it also may act as a strainer to entrap foreign particles. A separate strainer as described is desirable, however, because under normal operation of the air conditioning system, the muffler passes mostly vaporous refrigerant which is more difficult than liquid to pass through a partially clogged straining member. Therefore, when the strainer entraps the foreign material before it can become lodged in the orifice tube, it also prevents it from reaching the muffler. This keeps the muffler clean and the system functioning at maximum efficiency.

Therefore, an object of the present invention is to provide a capillary tube type expansion device for an air conditioning system utilizing a relatively short length capillary tube supported in a fluid housing and having a noise suppressing muffler member surrounding the outlet of the capillary tube to prevent the escape of sibilant noises which are caused by the passage of gas through the capillary tube.

A further object of the present invention is to provide a refrigerant expansion device for an air conditioning system including a relatively short length capillary tube supported in a housing and having a strainer member surrounding the inlet end of thecapillary tube and a muffler member surrounding the outlet end of the capillary tube which are formed of sintered metal to readily pass refrigerant therethrough but entrapped foreign particles and muffle noise'produced at the outlet of the capillary tube.

A still further object of the present invention is to provide a refrigerant expansion device for use in an air conditioning system including a short length capillary tube located in a tubular housing by a cylindricalmemher which partially surrounds the expansion tube and contacts the tube at a circular end; the cylindrical supporting member also retains a cup-shaped strainer member and muffler member around the inlet and outlet end of the orifice tube respectively.

Other objects and advantages of the present-invention will be readily apparent from the following detailed description, reference being had to the accompanying drawings.

IN THE DRAWINGS FIG. 1 is a schematic view of an automobile air conditioning system including the subject expansion device; 1

FIG. 2 is a sectioned view of the liquid accumulator shown in FIG. 1; I

FIG. 3. is an enlarged sectioned view of one embodiment of the subject expansion device; and

FIG. 4 is a fragmentary sectioned view of another embodiment of the subject expansion device.

In FIG. 1 of the drawings, an automobile air conditioning system is schematically illustrated. A refrigerant compressor 10 is shown with a pulley assembly 12 attached to one end of a drive shaft extending from the compressor. The pulley I2 is adapted to be connected by a belt drive to an internal combustion engine of the vehicle for rotating the compressor. The outlet of the compressor 10 includes a tube or conduit 14 which extends from the end of the compressor to a fitting 16 which connects it to a high pressure flexible hose l8. Hose 18 in turn is connected by a fitting 20 to the inlet 22 of a condenser 24.

Condenser 24 is normally located in the forward portion of the engine compartment to receive air flowing through the grill as the automobile moves. The compressed refrigerant from the compressor 10 is cooled and liquified in the condenser 24. The outlet 26 of condenser 24 is connected to an inlet 28 of an expansion means 30 by a fitting 32. The expansion means 30 is shown in more detail in FIGS. 3 and 4. Its function is to expand high pressure refrigerantfrom the condenser to a lower pressure condition. The outlet 34 of the expansion means 30 is connected to an inlet 36 of an evaporator 38. The low pressure liquid refrigerant is vaporized in the evaporator 38 as heat is absorbed from air passing over the evaporators exterior surfaces. The refrigerant vapor is then discharged from the evaporator 38 through an outlet 40 which is connected to an inlet 42 of aliquid accumulator 44. The liquid accumulator 44 is shown in more detail in FIG. 2. The outlet 46 of a liquid accumulator 44 is in turn connected by a fitting 48 to the inlet 50 of compressor to complete the cycle.

The expansion means is best shown in FIG. 3 and includes an outer tubular housing 54 having an enlarged diameter end 56. The inlet 28 extends from condenser 24 and is adapted to be inserted into the enlarged diameter end 56 of the expansion means 30. A crimped portion 58 in the inlet tube 28 limits the insertion of inlet 28 into tubular member 54. An O-ring 60 prevents refrigerant leakage between inlet 28 and member 54. The threaded outer portion 72 of tubular member 54 is adapted to engage a fitting 32 shown in FIG. 1 which is utilized to attach inlet 28 to the expander housing 54.

A capillary tube type expander is positioned within the tubular member 54 and includes 'a short length, small diameter orifice tube 62 through which refrigerant must pass from the condenser to the evaporator and which by a throttling process reduces refrigerant pressure. Orifice tube 62 is supported at its mid-portion by a collar member 64 which isengaged at its outer edge by a tubular support member 66. The tubular member 66 has a spun over end flange 68 which engages the shoulders 70 formed by the enlarged diameter end portion 66. The engagement of flange 68 with shoulder 70 axially positions the orifice tube assembly within the tubular member 54. I

The orifice tube 62 is a relatively small diameter tubular member easily blocked by the lodging of foreign material which may be carried by refrigerant in its passage through the tube; To prevent blocking of the orifice tube, a sintered metal strainer 74 is held by the tubular support member 66-around the inlet end portion 76 of orifice tube 62.

Orifice tube expanders such as shown in FIG. 3 characteristically emit an unpleasant and sometimes alarming hissing or sibilant noise when the compressor is deactivated. This is caused by the formation of high pressure vaporous refrigerant in the condenser immediately after de-activation of the compressor. The high pressure vaporous refrigerant flows through the orifice tube 62 at a greater velocity than liquid refrigerant and thus produces a high pitched hissing noise. The subject orificetype expander provides a sintered metal muffler 78 which is supported by the member 66 about the outlet end portion 80 of theorifice tube 62. The muffler prevents the emitted sibilant noises from becoming audible to the operator of the automobile.

In the embodiment shown in FIG. 3, the orifice tube 62 is attached to member 64 by braising at 82. Likewise, the strainer 74 is attached to a crimped portion 84 of member 66 by braising at 86. The muffler 78 is braised to member 64 and 66 at 88.

I The refrigerant which is vaporized in evaporator 38 passes through outlet 40 into a liquid accumulator 44 which is detailed in FIG. 2. The inlet 42 of the accumulator 44 is formed in an upper end cap which is braised or welded at 92 to a lower cylindrical housing portion 94. The inlet 42 is aimed in a tangential direction to direct refrigerant in a spiral path around the inside of the accumulator 44. The vaporous refrigerant which flows into the liquid accumulator may contain liquid refrigerant. It is undesirable for liquid refrigerants to pass into the compressor 10. Therefore, the outlet of the liquid accumulator provides a tube 96 which 94. The upper end 100 of the tube 96 is opened to form a passage for vaporous refrigerant to flow from the liquid accumulator to the compressor 10. An annular wall 102 between the inlet 42 and the outlet tube 96 prevents liquid refrigerant from inlet 42 from flowing directly into the open end 100 of tube 96. In the bottom of member 96, a doughnubshaped container 104 contains moisture absorbing material to remove any water mixed with the refrigerant.

In FIG. 4, another embodiment of the expansion device is shown which'is similar to FIG. 3 and includes orifice tube 62 which is supported by a circular member 64 braised at 82 to the tube. Member 64' is axially held between two threaded members 106 and 108 which are attached together at threaded portions 110 by a-surrounding collar 112. The strainer 74 and muffler 78 are attached tomembers 106 and 108 respectively by braising at 11.4. Collar 112 and member 106 engage a flange portion 116 of a tubular member 118 which corresponds to the member 66 in FIG. 3. Member 118 is axially held within a surrounding tubular member in a similar manner as member 66 in FIG. 3.

said compressor outlet for receiving refrigerant therefrom and for cooling and liquifying the refrigerant; expansion means fluidly connected to said condenser for receiving refrigerant therefrom and for reducing its pressure; an evaporator fluidly connected to said expansion means for receiving refrigerant therefrom and for vaporizing the refrigerant by the absorption of heat from air passing overthe exterior surface of said evaporator; a liquid accumulator fluidly connected to said evaporator for receiving refrigerant therefrom and passing mostly vapor refrigerant to said compressor inlet; said expansion means including a tubular member having a relatively small-internal diameter defining a restrictive passage for controlling the flow of refrigerant from said condenser to said evaporator; said tubular member having an outlet end for the discharge of refrigerant; a porous muffler member having a generally cup-like structure supported around said outlet end of said tubular member to suppress the escape of sibilant noises emitted from the outlet end of said tubular member upon passage of gaseous refrigerant through said restrictive passage immediately subsequent to deactivation of the air conditioning system.

2. An air conditioningsystem comprising: a refrigerant compressor having an inlet and an outlet for compressing refrigerant; a condenser fluidly connected to said compressor outlet for receiving refrigerant therefrom and for cooling and Iiquifying the refrigerant; expansion means fluidly connected to said condenser for receiving refrigerant therefrom and for reducing its pressure; an evaporator fluidly connected to said exextends through a port 98 in the bottom of the member pansion means for receiving refrigerant therefrom and for vaporizing the refrigerant by the absorption of heat from air passing over the exterior surface of said evaporator; a liquid accumulator fluidily connected to said evaporator for receiving refrigerant therefrom and passing mostly vapor refrigerant to said compressor inlet; said expansion means including a tubular member having a relatively small internal diameter defining a restrictive passage for controlling the flow of refrigerant from said condenser to said evaporator; said tubular member having an outlet end for the discharge of 5 refrigerant; a porous muffler member having a generally cup-like structure supported around said outlet end of said tubular member to suppress the escape of sibilant noises emitted from the outlet end of said tubular member upon passage of gaseous refrigerant through said restrictive passage immediately subsequent to deactivation of the air conditioning system; said muffler member being formed of sintered copper-based metal.

3. For use in an automobile air conditioning system including a refrigerant compressor, a condenser, an evaporator for vaporizing refrigerant by absorbing heat from air passing over its exterior surfaces and a liquid accumulator for storing excess refrigerant, an improved expansion means for reducing refrigerant pressure comprising: a housing having an inlet adapted to be fluidly connected to said condenser and an outlet adapted to be fluidly connected to said evaporator to pass refrigerant between said condenser and said evaporator; a member in said housing supporting a short through said restrictive passage immediately subse-' quent to deactivation of the air conditioning system. 

1. An airconditioning system comprising: a refrigerant compressor having an inlet and an outlet for compressing refrigerant; a condenser fluidly connected to said compressor outlet for receiving refrigerant therefrom and for cooling and liquifying the refrigerant; expansion means fluidly connected to said condenser for receiving refrigerant therefrom and for reducing its pressure; an evaporator fluidly connected to said expansion means for receiving refrigerant therefrom and for vaporizing the refrigerant by the absorption of heat from air passing over the exterior surface of said evaporator; a liquid accumulator fluidly connected to said evaporator for receiving refrigerant therefrom and passing mostly vapor refrigerant to said compressor inlet; said expansion means including a tubular member having a relatively small internal diameter defining a restrictive passage for controlling the flow of refrigerant from said condenser to said evaporator; said tubular member having an outlet end for the discharge of refrigerant; a porous muffler member having a generally cup-like structure supported around said outlet end of said tubular member to suppress the escape of sibilant noises emitted from the outlet end of said tubular member upon passage of gaseous refrigerant through said restrictive passage immediately subsequent to deactivation of the air conditioning system.
 2. An air conditioning system comprising: a refrigerant compressor having an inlet and an outlet for compressing refrigerant; a condenser fluidly connected to said compressor outlet for receiving refrigerant therefrom and for cooling and liquifying the refrigerant; expansion means fluidly connected to said condenser for receiving refrigerant therefrom and for reducing its pressure; an evaporator fluidly connected to said expansion means for receiving refrigerant therefrom and for vaporizing the refrigerant by the absorption of heat from air passing over the exterior surface of said evaporator; a liquid accumulator fluidily connected to said evaporator for receiving refrigerant therefrom and passing mostly vapor refrigerant to said compressor inlet; said expansion means including a tubular member having a relatively small internal diameter defining a restrictive passage for controlling the flow of refrigerant from said condenser to said evaporator; said tubular member having an outlet end for the discharge of refrigerant; a porous muffler member having a generally cup-like structure supported around said outlet end of said tubular member to suppress the escape of sibilant noises emitted from the outlet end of said tubular member upon passage of gaseous refrigerant through said restrictive passage immediately subsequent to deactivation of the air conditioning system; said muffler member being formed of sintered copper-based metal.
 3. For use in an automobile air conditioning system including a refrigerant compressor, a condenser, an evaporator for vaporizing refrigerant by absorbing heat from air passing over its exterior surfaces and a liquid accumulator for storing excess refrigerant, an improved expansion means for reducing refrigerant pressure comprising: a housing having an inlet adapted to be fluidly connected to said condenser and an outlet adapted to be fluidly connected to said evaporator to pass refrigerant between said condenser and said evaporator; a member in said housing supporting a short length, small inner diameter tube defining a restrictive passage through which refrigerant flows; said tube being supporTed between an inlet end portion extending from said support member toward the inlet of said housing and an outlet end portion extending from said support member toward the outlet of said housing; a generally cup-shaped member of porous sintered metal supported around the outlet end of said tube to suppress the escape of sibilant noises emitted from the outlet end of said tube upon passage of gaseous refrigerant through said restrictive passage immediately subsequent to deactivation of the air conditioning system. 